Abstract
According to the concept of circular economy, insects represent good candidates as aquafeed ingredients. Nevertheless, there are some potential chemical risks linked with insect consumption. In this study, we reared the teleost Danio rerio, used as an experimental model, with five experimental diets characterized by increasing levels (0%, 25%, 50%, 75%, and 100%) of full-fat Hermetia illucens (Hi) prepupae, substituting for fish meal (FM) and fish oil (FO). We investigated the presence of potentially toxic elements (PTEs) Cd, Pb, Ni, As, and Hg in larval (20 days), juvenile (2 months), and adult (6 months) fish. Quantitative determinations of Cd, Pb, Ni, and As were made with an atomic absorption spectrometer; the total mercury content was determined by a direct mercury analyzer. The substitution of FM and FO with Hermetia illucens meal led to a reduction in the content of some PTEs, such as Pb, As, and Ni, in fishfeed, leading to concentrations below the legal limit of undesirable substances in animal feed. By increasing the Hi meal dietary content, we observed in the Danio rerio specimens an increase in Cd, Pb, and Ni content and a reduction in As content for all life stages. Moreover, a general increase in the content of Cd, Pb, Hg, and Ni from larvae to juvenile was measured, while the shift of Danio rerio from the juvenile to the adult stage involved a significant increase in the content of Pb, Hg, and Ni. Larvae had a reduced ability to bioaccumulate metal(loid)s compared to juveniles and adults. In conclusion, the content of PTEs in Danio rerio is influenced both by the type of diet administered and by the life stage of the animal itself. This research demonstrates the possibility of using Hi prepupae as an aquafeed ingredient without exposing fish to a chemical risk and, in perspective, allows applying these eco-sustainable diets for the breeding of edible fish species, without endangering human health.
Highlights
On the basis of a forecast predicting a significant demographic increase of the global population, the Food and Agriculture Organization of the United Nations [1] estimates that world food production will have to increase by 60% to meet food needs
The content of potentially toxic elements (PTEs) were well below the legal limits set by Italian Legislative Decree 31/2001 [43], which regulates the quality of water intended for human consumption in order to protect human health from the negative effects deriving from water contamination
The substitution of fish meal (FM) and fish oil (FO) with Hermetia illucens meal in experimental diets led to a reduction in the content of some PTEs, such as Pb, As, and Ni, with concentrations for all studied PTEs below the legal limit of undesirable substances in animal feed given in [45]
Summary
On the basis of a forecast predicting a significant demographic increase of the global population (over nine billion people by 2050), the Food and Agriculture Organization of the United Nations [1] estimates that world food production will have to increase by 60% to meet food needs. Fish meal is made by drying and grinding the carcasses of fish, leading to a concentration of toxic elements present in the fish themselves. This fact, together with the contamination of marine environments, led to a product that contains excessive amounts of pollutants [12]. PTEs have a high degree of toxicity and a wide distribution in the environment [18,19,20,21,22] Metals such as arsenic (As), nickel (Ni), cadmium (Cd), lead (Pb), and mercury (Hg) rank among the priority elements that are of great public health significance. Consuming foods containing PTEs can lead to numerous human health risks, such as renal disfunction and cancer (Cd) [24], neurological deficits (Pb) [25], dementia and dysarthria (Hg) [26], cardiovascular disorders and skin problems (As) [27], DNA damage, and immunologic and neurologic problems (Ni) [28]
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